AT&T got its lowest marks in the survey for its voice services, as it was the only wireless carrier in the United States to receive below-average marks for its voice quality. Verizon received above average marks for its voice service while T-Mobile and Sprint both received average marks. AT&T also received subpar remarks across the board for its customer service while receiving average marks for its text-messaging and data services.

AT&T also had the most expensive average monthly bills for two-line plans, the survey found, as its wireless voice services clocked in at an average of $86 a month and its wireless voice plan with data averaged $134 per month. Verizon had the second most expensive average monthly bill, with an average voice bill of $83 per month and an average voice and data bill of $126 per month. T-Mobile and Sprint offered the least expensive monthly voice and data bills at an average of $114 per month.

The results of the survey come at a bad time for AT&T, which has already been on the defensive over Verizon's ads attacking its 3G coverage. Verizon's "There's a Map for That" ads typically show AT&T users struggling to use applications on their mobile devices while Verizon customers happily watch live streaming videos. The ads then display maps that show the total geographical reach of 3G coverage for each carrier, with Verizon's map showing a far larger area of the country covered by its 3G service.

The survey, which was based on responses from more than 50,000 wireless customers living in 26 metropolitan areas, showed that Verizon was the only carrier to receive above average marks in all aspects of its service, from its voice to its SMS and data to its customer service. Verizon also came out on top of the rankings in all 26 cities surveyed.

T-Mobile, despite rating as average in its voice and data services, nonetheless received above average scores for its customer support. Sprint, last year's lowest-ranked carrier, continued to be plagued by poor customer service ratings as the survey rated the carrier the worst at resolving issues.

While AT&T received bad news on the customer satisfaction front, the carrier can take solace in the fact that it still has the most highly-rated smartphone in the industry. According to Consumer Reports' survey of smartphone users, the iPhone 3GS is far and away the top-rated smartphone, earning high marks for its display, its navigation capabilities, its Web browsing, its multimedia quality and its battery life.

Also receiving good scores in the smartphone survey were the Nokia N97 for AT&T, the T-Mobile myTouch, the HTC Touch Pro2 for Verizon, the HTC Imagio for Verizon and the Samsung Omnia for Verizon. The lowest rated smartphones in the survey were the BlackBerry 8830 for Verizon, the BlackBerry Curve 8330 and BlackBerry Pearl 8130 for Sprint, the Nokia Surge for AT&T and the T-Mobile Sidekick.